Extended oil filler tube



Oct. 28, 1969 D. E. BRAUN 3,474,884

EXTENDED OIL FILLER TUBE Filed March 14, 1968 .nnlllllllllllllll IIIIHIH lllllllllll -llllllllllllllllunm.

17521122 .EBraun Jay b'-- v a United States Patent US. Cl. 184-1 6 Claims ABSTRACT OF THE DISCLOSURE A self-supporting plastic tube threaded into the oil filler opening in the crankcase of a single cylinder internal combustion engine has its mouth closed by a cap to which a dip stick is secured. The cap has a nipple that inserts into the mouth of the tube. and is releasably retained in place by the engagement of detent-like abutrnents on the nipple under a ledge formed by a constriction in the tube,

and to prevent plunger action as the nipple is inserted into the tube, the nipple has longitudinal slots that provide air passages past the constriction.

This invention relates broadly to small single cylinder internal combustion engines, and refers more particularly to a combined filler tube and dip stick to facilitate the introduction of oil into the engine crankcase and measurement of the oil level therein.

Manufacturers of engine powered lawn mowers, and other appliances have recently adopted designs for their equipment which require that it be possible to introduce the oil into the engine crankcase at the very top of the engine. To meet this need, it was found expedient to attach an extension tube to the oil filler port of the engine. This was simple enough, as was also the provision of a cap to close the mount of the extension tube and held in place by the insertion of a nipple at the underside of the cap into the mouth of the tube, the cap having a dip stick fixed thereto to reach down through the tube and into the crankcase.

However, it was soon discovered that the oil level readings obtained with this combined filler tube and dip stick were not accurate. The difficulty was traced to a plunger action which resulted from the insertion of the nipple into the mouth of the tube.

The purpose and object of this invention is, therefore, to provide an improved oil filler tube and dip stick of the character described wherein false oil level indications are eliminated by a novel way of preventing the observed plunger action during insertion of the dip stick.

Another object of this invention is to provide a combined oil filler tube and dip stick which is simple in design and construction and which lends itself well to use with vertical shaft single cylinder engines of the type extensively used by manufacturers of engine powered lawn mowers and other applicances and equipment designed for home owners use.

With these observations and objects in mind, the manner in which the invention achieves its'purpose will be appreciated from the following descriptionvand the accompanying drawings. This disclosure is intended merely to exemplify the invention. The. invention is not limited to the particular structure disclosed, and changes can be made therein which lie within the scope of the appended claims without departing from the invention.

The drawings illustrate one complete example of the physical embodiment of the invention constructed according to the best mode so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a perspective view of a portion of a vertical shaft signle cylinder internal combustion engine equipped with the combined oil filler tube and dip stick of this invention;

FIGURE 2 is a view partly in elevation and partly in longitudinal section, illustrating the combined oil filler tube and dip stick;

FIGURE 3 is a perspective view of the upper end of the filler tube and the cap, shown separated and with the dip stick broken away; and

FIGURE 4 is a cross sectional view through FIGURE 2 on the plane of the line 44.

Referring to the drawing, the numeral 5 designates generally a vertical shaft single cylinder internal combustion engine having a crankcase 6 which constitutes the lower portion of this engine. Protruding from one side of the crankcase is a hollow projection 7 with an upwardly facing top wall 8 provided with an oil inlet opening 9. The opening 9 is tapped and has the lower end portion 10 of an extension tube 11 threaded therein. A flat bottomed slightly undercut flange 12 encircles the tube directly above its threaded lower end portion to have oil tight sealing engagement with the top wall 8.

The tube 10 is a plastic molding of sufficient rigidity to be self-supporting when threaded into the oil inlet opening 9. At its upper end the tube has a funnel-like enlargement 13, the mouth of which is at a level approximately in line with the top wall 14 of the engine. The funnel-like enlargement has a cylindrical upper wall portion 15, the edge or rim of which lies in a plane normal to the axis of the tube, and a downwardly and inwardly sloping conical lower portion 16. Reinforcing ribs 17 provide stiffness at the junction of the cylindrical and conical wall portions.

At the junction of the conical lower portion 16 of the enlargement 13 with the tube proper, there is a constriction 18 in the diameter of the tube. This constriction provides a downwardly facing shoulder or ledge for a purpose to be described.

The mouth of the funnel-like enlargement at the end of the tube is closed by a removable cap 19 to which a dip stick 20 is fixed for insertion through the tube and into the hollow extension of the crankcase when the cap is placed in position closing the mouth of the'tube. To'

hold the cap in place, a nipple 21 which projects down wardly beyond the constriction 18. On the lower extremity of the nipple there is a" slightly bulbous enlargement 23 which forms an upwardly facing shoulder so positioned with respect'to the underside of the capthat when the cap is seated on'the edge or-ri m of the enlarged mouth of the tube, this shoulder engages snugly under the ledge provided by the constriction 18 'and'thereby holds the cap against accidental displacement! A gasket 25 at the underside of the cap engages the edge or rim to provide a reasonably tight seal.

It will be noted that the nipple is hollow for a substantial part of its length which'formation results from a bore 26 formed in the nipple at the time the cap is molded. Because of the hollow nature of the nipple, its Wall is sufficiently pliable to permit the enlargement 23 to snap past the constriction 18,.but' in doing so a distinct plunger action would occur which, if not eliminated, would result in a false oil level indication on the dipstick during measurement of the oil level. Thisobjection -;is overcome by a plurality of longitudinal slits 27 in the wall of the hollow lower portion of the nipple. In the present case, there are four such slits, equispaced around the circumference of the nipple and extending from the extremity thereof well above the enlargement 23. Hence, the slits provide air passages past the constriction 18 as the cap is applied and the dip stick is lowered into the crankcase extension 7, to vent the space in the tube below each of which has a part of the enlargement 23 thereon, and thus facilitate passage of the enlargement past the constriction and under the ledge formed thereby.

What is claimed in my invention is:

1. In an internal combustion engine having a crankcase adapated to hold a supply of oil, the crankcase having a port in an upwardly facing wall thereof through which which oil may be introduced:

(A) an upright tube having its lower end secured to said wall of the crankcase in open communication with the port therein and having its upper end at a readily accessible location on the engine, the upper end of the tube being open and providing a mouth into which oil may be poured for introduction into the crankcase;

(B) a cap to close the mouth of the tube, the cap having a nipple at its underside to enter the mouth of the tube a the cap is put in place;

(C) cooperating detent means on the. nipple and the tube, engageable with one another as the nipple enters the mouth of the tube, to hold the cap in place, said detent means comprising a downwardly facing annular shoulder on the wall of the tube having an uninterrupted inner edge, and upwardly facing shoulder means on the nipple. engageable under said annular shoulder;

(D) a dip stick fixed to the cap to extend through the tube and into the crankcase, whereby removal of the cap and withdrawal of the dip stick afiords an indication of the level of the oil in the crankcase; and

(E) means to prevent plunger action resulting from insertion of the nipple into the tube past said annular downwardly facing shoulder, said means comprising longitudinal slits in the nipple extending above and below its downwardly facing shoulder means, driving the nipple into spaced resilient fingers on which the upwardly facing shoulder means is located and providing air passages between the fingers to communicate the space in the upper end of the tube during application of the cap.

2. In an internal combustion engine having a crankcase adapted to hold a supply of oil, the crankcase having a port in an upwardly facing wall thereof through which oil may be introduced:

(A) an upright tube having its lower end secured to said wall of the crankcase in open communication with the port therein and having its upper end at a readily accessible location on the engine, the upper end of the tube being open and providing a mouth 4 a into which oil may be poured for introduction into the crankcase;

(B) means defining a constriction in the upper end '(D) an annular enlargement encircling the nipple to snap past the constriction and to engage under saiddownwardly facing ledge and hold the cap in place;

(E) a dip stick fixed to the cap to extend through the 4 tube and project into the crankcase when the cap in -is position closing the mouth of the tube; and

(F) means to prevent plunger action resulting from the insertion of the nipple into the mouth of the tube as the cap is applied, said means comprising longitudinally extending slits in the nipple extending above and below said enlargement and dividing the portion of the nipple at which the enlargement is located into resilient fingers to facilitate snapping the enlargement past the constriction and providing air passages between the fingers past the constriction.

3. The structure of claim 2, further characterized in that the upper end portion of the tube is shaped to provide a funnel-like enlargement having a downwardly and inwardly sloping wall which terminates at the constriction.

4. The structure of claim 3, further characterized by a gasket at the underside of the cap encircling the nipple and engaging the rim of the funnel-like enlargement when the cap is in place closing the mouth of the tube.

5. The structure of claim 2, further characterized in that the slitted portion of the nipple is hollow.

6. A combined oil filler tube and dip stick comprising:

(A) a self-supporting plastic tube, one end portion of which is externally screw threaded to enable the tube to be screwed into a tapped oil filler hole in the crankcase of an engine;

(B) the opposite end portion of the tube being enlarged and shaped to provide a funnel-like mouth for the tube;

(C) the wall of the tube axially inward of its funnellike mouth being shaped to provide a constriction defining an axially inwardly facing ledge;

(D) a cap to seat upon the rim of the funnel-like mouth of the tube, the cap having a nipple extending therefrom to telescope into the tube past said constriction;

(E) an annular enlargement on the end portion of the nipple to snap past said constriction as the cap is applied and to engage under said ledge and hold the cap in place seated upon the of the funnellike mouth of the tube, the end portion of the nipple being hollow and having a plurality of longitudinally extending circumferentially spaced slits extending to opposite sides of the annular enlargement, dividing said hollow end portion of the' nipple into a plurality of resilient fingers and providing air passages to communicate the space within the tube at opposite sides of its constriction as the cap is applied; and

(G) a dip stick fixed to the cap and projecting through and beyond the nipple to reach beyond the threaded end of the tube when the' cap is in place.

References Cited UNITED STATES PATENTS Re. 26,422 7/1968 Stade et a1. 33-1267 1,354,788 10/1920 Wallace. 2,032,800 3/ 1936 Haltenberger 33-126] 2,375,096 5/1945 Francisco. 3,262,602 7/1966 McConnell et al 220-60 3,371,418 3/1968 Moeller 33l26.7

FRED C. MATTERN, 1a., Primary Examiner MANUEL ANTONAKIS, Assistant Examiner us. (11. X.R. 33- 126.7; 1846 

